Hydraulically tuned magnetron



June 1, 1965 E. c. DENCH HYDRAULICALLY TUNED MAGNETRON 3 Sheets-Sheet 1 Filed Jan. 30, 1961 TO POWER SUPPLY OUTPUT w M ,0 l 2 3 w 4 1M 2 lklll I 11:1 H2 1 I). II I 4 l I- I 3 I- I. 1 I. I I 1 m IWW 5 7. ll -1 w 0 In. HI PHH "a HVVENTOR EDWARD C. BENCH #W AGENT June 1, 1965 E. C. DENCH HYDRAULICALLY TUNED IIAGNE'I'RON 3 Sheets-Sheet 2 Filed Jan. 30, 1961 INVENTOIF EDWARD 6'. DE/VCH f TQM AGENT June 1, 1965 E. c. DEN-CH 3,187,220 I HYDRAULIGALLY TUNED MA'GNETRON File d Jan. 30, 1961 I 3 Sheets-Sheet s I "To POWER SUPPLY I as 55 5? 5a 520 l 54 I s I I CONTROL 0| L POSITION VALVE PUMP TRANSDUCE l summms SERVO 56 AMPLIFIER MOTOR MANUAL 59 SERVO P' cog- 3M AMPLIFIER A aewr 3 187 220 nrnaauucarriz romeo MAoNErnoN Edward C. Bench, Needham, Mass, assignor to Raytheon Company, Lexington, Mass, a corporation of Delaware- Filed Jan. 30, 1961, Ser. No. 85,540

7 Claims. (Cl. 315-3955) This invention relates to magnetrons and more particularly to a magnetron structure having hydraulically actuated parts for tuning the magnetron rapidly over a wide range of frequencies. In some applications of magnetrons it is required to tune the magnetron over a wide frequency band at a relatively high rate. For example, some systems require a magnetron to be tuned at a rate as high a '250,000 mc./ second/ second over bandwidths as high as fifty percent. In the past, tuning of a magnetron has been accomplished in a variety of manners. For example, the pulling efiect is often employed to tune a magnetron over a fraction of a percent bandwidth by mismatching a load coupled to the output of the magnetron. The pushing effect is also employed by varying anode voltage, although generally this effect is undesirable and is eliminated wherever possible even though tuning over a somewhat wider bandwidth (about one percent) can be obtained. his quite apparent that neither'of these methods of tuning are satisfactory to accomplish the requirements such as set forth above. 1

Recently, conductive plungers have been employed in 3 187,22 0 Patented June 1 1965 tional hydraulic actuator connected to .the plungers for positioning the plungers in the cavity; and

FIG. 3 illustrates a servo loop for controlling a hydraulically tuned magnetron such as shown in FIG. 2. Turning first to FIG. 1 there is shown a sectional view of a conductive envelope 1 enclosing anode block 2 having a plurality of cylindrical cavities 3 cut in the block and substantially parallel to the axis of the envelope. Plunger cylinders 4 preferably composed of highly conductive material are inserted in each of thecavities as shown in the figure. ,The plungers are preferably of smaller diameter than the cavities but have the same general shape magnetrons which are movable in and out of the cavity spaces to accomplish tuning. A cylindrical plunger is usually employed which has the same general conforrna tion as the cavity but is somewhat smaller so that it may fit within the cavity without touching the sides. The magnetron tube is sometimes equipped with a diaphragm arrangement which can be flexed externally to thereby move the plungers in and out of the cavities tuning the magnetron over a relatively wide frequency hand. For example, in some structures of this type fifty percent bandwidth tuning has been accomplished. However, heretofore such plunger tuned magnetrons have not been readily tuned at high rates, such as mentioned above, but are usually adjusted manually by an operator to produce a given frequency, and once the frequency is established, it is not changed again for some time. Therefore, it is an object of the present invention to provide a magnetron which can be tuned rapidly over a wide frequency band.

In accordance with the present invention, hydraulic actuating means are coupled to plungers located within the magnetron envelope to position the plungers within the cavities. In one embodiment the plungers are mounted upon a plate which is supported by a shaft extending through the tube envelope to an enclosure containing hydraulic fluid and a springload. The hydraulic fluid acts against a spring load moving the plungers within the cavities. Another embodiment includes a hydraulic actuator coupled to one end of the shaft for driving it in translation'to move the plungers in or out of the cavities. Two hydraulic lines conduct different hydraulic forces to the actuator to move the plungers in or out of the cavities.

Another useful embodiment of the invention includes a servo control loop coupled to the hydraulic actuator and responsive to a control signal and a signal representing the position of the plungers within the cavities.

Other features and objects of the invention will be more apparent from the following specific description taken in conjunction with the drawings in which:

FIG. 1 illustrates a sectional view of a magnetron with a spring loaded hydraulic actuator for positioning the plungers;

FIG. 2 illustrates another embodiment with a bidirecas the cavities so that when inserted into the cavities they occupy an appreciable portion of the cavity but do not touch the walls thereof.

Plungers 4 are supported by disc 5 which is in turn supported on the end of shaft 6. Shaft 6 is slidably supported by sleeve bearing '7 which is fixed to the walls of envelope 1. The shaft 6 thus extends through the envelope wall into a hydraulic space 8. A hydraulically sealed bellows 9 is connected between envelope 1 and support plate 5 enclosing another hydraulic space 10 substantially concentric with the axis of the tube and sealed from the internal vacuum of the tube. An orifice or port 11 is provided through theenvelope 1 to permit the flow of hydraulic fluid from space 8 to space 10 app-lying a hydraulic force against the bottom of support plate 5 The hydraulic force acts against the resistance of a spring 12' in space 8 which is loaded betweendisc 13, attached to the end of shaft 6, and the envelope 1.

The upper part 14 of the'magnetron-containing the cathode is shown removed to permit the view. of the anode block and plungers. The upper part includes a cathode 15 which extends into the central opening 16 in the anode block, a plate in which is sealed to envelope 1 forming a complete vacuum-tight envelope and a connector 17 carrying cathode leads to a power supply.

An output may be coupled from the tube employing any of a variety of well-known techniques; for example, a waveguide 18 may be coupled to one of the cavities such as 19 through an opening 20 in envelope 1 which is covered by, for example, a'ceramic window 21 sealed to the envelope providing a vacuum-tight seal between waveguide 18 and the envelope.

In operation it is preferred that a fixed potential be maintained between cathode 15 and anodeblock 2. The

erably connected to the bottom of space 8.

Another embodiment of the present invention for positioning the plungers within the cavities of a magnetron is shown in FIG. 2. This embodiment employs two hydraulic lines, one applying pressure to move the plungers deeper into the cavities and the other applying pressure to move the plungers out of the cavities. The device in FIG. 2 is shown broken into two parts 25 and 26 each enclosed by a part of the envelope 27 to permit a better view of the plunger mechanism within the tube. The upper part 25 shown cut away includes an anode block 28, an output waveguide 29 coupled to one of cavities 30 in much the same manner as shown in FIG. 1, a cathode 31 and a connector 32 coupling heater and potential leads tothe cathode. A.

The lower part 26 also shown cut away includes 'envelope 27 enclosing plunger guide 33 which is attached to the envelope 27, plungers 34 aligned and guided by openings 35 in guide 33, support plate 36 for supporting the plungers, a shaft 37 for holding support plate 36 and vacuum-tight bellows 38 connected between plate 36 and envelope 27. y

' Shaft 37 is slidably supported by sleeve 39 permitting position plungers 3% within the cavities of anode. block 28. Two hydraulic lines 42 and 43 are provided for conducting controlled hydraulic pressures to actuator 41 for within the sleeve. The

causing shaft 37 to move in translation positioning the h plungers in the cavities. 1

Actuator 41 might, for example, consist of a piston 44 threaded to the end of shaft 37 and driven in translation within block 45. The piston is equipped with a flange portion 46 machined to fit snugly into a cavity 47 in the block. Rubber sealing rings such as 48 are provided on each 'sde of the cavity 47 providing a seal around the cavity and rubber ring 49 is provided between flange 46 and block 45 to insure a seal between the flange and the block. In operation hydraulic fluid conducted by lines 42" and as is applied to the upper and lower corners, respectively, p

of cavity 47. When the pressure in line 42 exceeds that in 43, piston-44 will move downward pulling shaft 37 downward and removing the plungers 34 from the cavities 39 in the anode block. One the other hand, when pressure in line 43 exceeds that in 42, piston 44 will be forced upward inserting the plungers into the cavities, and when pressures are equal, the plungers will remain stationary within the cavities.

Turning next to FIG. loopfor controlling the frequency output of the magnetron illustrated in FIG. 2. The magnetron 50, as shown in FIG. 3,- includes a magnet 51 and hydraulic actuator 52 with hydraulic lines 53 and 54 connected between the actuator and a control valve 55. Actuator52 ispreferably sirnilar to actuator 41' shown in detail in FIG. 2. A servo motor 56 actuates the valve which in turn adjusts the pressure in lines 53 and Sl derived from, for example, oil pump, 57 which supplies pressure to the valve. In operation the position of the plungers in the" cavities is detected by position transducer 58 coupled to the piston 52a in hydraulic actuator 52 so that the transducer is.

mechanically actuated by motion of the piston. The electrical output from the transducer 58 is compared with 3 there is shown a servo-control electromagnetic waves and a body composed substantially of conductive material movably disposed within said cavity comprising means within said envelope for supporting said body, flexible means coupled to said support'body and said envelope and enclosinga sealed spaced between said support body and said envelope, means attached to said support body extending through said envelope into 'a second sealed space and attached to actuating means located therein and means conducting a pressurized fluid to at least one of said sealed spaces for moving said actuating means whereby the position of said body in said cavity is controlled.

2. An electron discharge device including an evacuated envelope enclosing at least one cavity for propagating electromagnetic waves and a body composed substantially of conductive material movably disposed within said cavity comprising means within said envelope for supporting said body, flexible means coupled to said support body and said envelope and enclosing a sealed spaced between said supportbody and said envelope,'means attached to said support-body within said space extending through said envelope into a second sealed space and attached to actuating means' located therein and means conducting a pressurized fluid to at least one of 'said sealed spaces for moving said actuating means whereby the position'of said body in said cavity iscontrolled. v

a 3. An electron discharge device including an evacuated envelope enclosing at least one cavity for propagating electromagnetic waves and a body composed substantially in said space extending through said space to an opening in said envelope into a'second sealed space. and attached to actuating means located therein and means conducting a control signal from, for example, manual control potentiometer 59. Comparison of these signals may be made in, for example, a summing amplifier 60 which producesa positive or negative output voltage depending on the relative magnitudes of signals from the transducer and potentiometer.

Whenthe signals are of equal magnitude, the output summing amplifier 60 isa null or zero. The control loop is completed by coupling the output of amplifier 60 to a servo amplifier 61 which energizes the motor 56. In some embodiments it may be desirable to further extend the control loop of the magnetron by replacing manual control potentiometer 59 with a circuit responsive to the frequency output of the magnetron. The replacement circuit may consist of, for example, a discriminator producing a control signal somewhat similar to the control signal produced by the control potentiometer. In other embodiments it may be desirable to cause the output frequencies of the magnetron to lock onto and follow an incoming frequency signal. In this case the incoming signal might be applied to a discriminator to produce the control signal equivalent to the output of the control potentiometer.

While there is described herein various embodiments of the present invention generally including hydraulic actuated means for positioning tuning plungers within magnetron cavities and servo-control-systems associated therewith, it should be clearly understood that these embodiments are made only by way of example and do not limit the spirit or scope of the invention as set forth in the following claims.

What is claimed is:

1. An electron discharge device including an evacuated envelope enclosing at least one cavity for propagating a pressurized fluid to at least one of said-sealed spaces for moving said actuating means whereby the position of said body in said cavity is controlled.

4. An electron discharge device including an evacuated envelope enclosing at least one cavity for propagating electromagnetic waves and a body of substantially conductive material movably disposed within said cavity comprising means within said envelope for supporting said body, flexible means, providing a hermetic seal between said support body and said envelope and fixedly secured to both said support body and said envelope and within said envelope enclosing a space between said support means and said envelope, a shaft attached to said support means disposed within said space and extending through 'said envelope into an enclosure, means conducting a pressurized fluid to said enclosure and an opening between said enclosure and said space permitting the flow of said fluid therebetween whereby fluid pressure moves said body within said cavity. 7 V

5. An electron discharge device including an evacuated envelope enclosing at least one cavity for propagating electromagnetic waves and a body of substantially conductive material movably disposed within said cavity comprising means within said envelope for supporting said body, a diaphragm fixedly attached to said envelope and said support means hermetically sealing a space between said support means and said envelope, a shaftattached to said support means disposed within said space and extending through said envelope into an enclosure, a spring in said enclosure loaded between said shaft and saidenvelope, means conducting a pressurized fluid to said second space and an opening between said enclosure and said space permitting the flow of said fluid therebetween whereby fluid pressure moves said body within said cavity in opposition to said spring load.

6. An electron discharge device including an evacuated envelope enclosing at least one cavity for propagating electromagnetic Waves, a body movably positioned Within said cavity, means Within said evacuated envelope for supporting said body, a shaft attached at one end to said supporting means and extending through said envelope wall, a sealed enclosure attached between said supporting means and said envelope Wall, another enclosure enclosing the other end of said shaft and means conducting pressurized fluid to said other enclosure for positioning said body in said cavity.

7. An electron discharge device including an evacuated envelope enclosing a plurality of elongated cavities disposed With axes substantially parallel to an axis of said device, a plurality of bodies composed substantially of conductive material each aligned with a difiierent one of said cavities and attached to a common support plate, a shaft extending within said envelope for supporting said plate at one end, a vacuum seal between said plate and said envelope forming a sealed space therein, an adjustfluid barrier between said sealed space and said other end of said shaft, a second sealed space enclosing at least a portion of said piston and means conducting pressurized fluid to said second sealed space whereby said bodies are positioned within said cavities along the axes thereof.

I References Cited by the Exan'iiner UNITED STATES PATENTS 2,589,885 3/52 Sonkin 31549.59 2,621,311 12/52 La Rue 313 14s X 2,779,904 1/57 Barron 328-1 x 2,950,703 8/60 Fletcher et al. 121 41 E 2,992,361 7/61 Rychlik 313-148 I FOREIGN PATENTS 636,527 5/50 Great Britain.

DAVID J. GALVIN, Primary Examiner.

ably positioned piston at the other end of said shaft, a 20 ARTHUR GAUSS, JAMES D. KALLAM, Examiners. 

1. AN ELECTRON DISCHARGE DEVICE INCLUDING AN EVACUATED ENVELOPE ENCLOSING AT LEAST ONE CAVITY FOR PROPAGATING ELECTROMAGNETIC WAVES AND A BODY COMPOSED SUBSTANTIALLY OF CONDUCTIVE MATERIAL MOVABLY DISPOSED WITHIN SAID CAVITY COMPRISING MEANS WITHIN SAID ENVELOPE FOR SUPPORTING SAID BODY, FLEXIBLE MEANS COUPLED TO SAID SUPPORT BODY AND SAID ENVELOPE AND ENCLOSING A SEALED SPACED BETWEEN SAID SUPPORT BODY AND SAID ENVELOPE, MEANS ATTACHED TO SAID SUPPORT BODY EXTENDING THROUGH SAID ENVELOPE INTO A SECOND SEALED SPACE AND ATTACHED TO ACTUATING MEANS LOCATED THEREIN AND MEANS CONDUCTING A PRESSURIZED FLUID TO AT LEAST ONE OF SAID SEALED SPACES FOR MOVING SAID ACTUATING MEANS WHEREBY THE POSITION OF SAID BODY IN SAID CAVITY IS CONTROLLED. 